// The Prototypes
MovieClip.prototype.oldCreateTextField = MovieClip.prototype.createTextField;
MovieClip.prototype.createTextField = function(name, depth, x, y, width, height){
this.oldCreateTextField(name, depth, x, y, width, height);
return this[name];
}
// Usage
var cowTF = _root.Farm.Barn.createTextField("Cow", 10, 50, 50, 100, 20);
cowTF.text = "moo";